Method of boring rock

ABSTRACT

The method sets forth a boring or tunneling of rock by independently applying only thrust force to rock cutters which are engaged with a surface of the rock, withdrawing the rock cutters, indexing them rotatably, and repositioning the same in engagement with the rock surface again and re-applying thrust. The method comprises performing these steps repetitively, indexing the cutters fully circularly sequentially, between surface-engagement and thrusting cycles, to define a circular bore. The apparatus disclosed comprises an embodied means for carrying out the novel method.

' United States Patent Coski Dec. 16, 1975 [5 METHOD OF BORING ROCK 3,221,824 12/1965 Self 175/19 175 20 X [75] Inventor: William D. Coski, Seattle, Wash. 3438452 4/1969 Bernard et d1 [73 Assignee: Ingersoll-Rand Company, Woodcliff FOREIGN PATENTS OR APPLICATIONS Lake, NJ, 678,494 9/1952 United Kingdom 175/77 [22] Filed: 1975 Primary Examiner-David H. Brown [21] Appl. No.: 550,931 Attorney, Agent, or FirmBernard .1. Murphy 52 US. Cl. 175/62; 175/162; 175/203 ABSTRACT [51] Int. Cl. E21B 7/00; E21B 19/08 h h d Sets f th a boring or tunneling of rock by [58] Field of Search 175/57, '62, 19, 20, 77, independently applying only thrust force to rock 175/162 203 ters which are engaged with a surface of the rock, withdrawing the rock cutters, indexing them rotatably, [56] References cued and repositioning the same in engagement with the UNITED STATES PATENTS rock surface again and re-applying thrust. The method 1,200,119 [0/1916 Keeler 175/19 comprises pflforming these p repetitively, index- 2,517,494 8/1950 Kiss et a1. ing the cutters-fully circularly sequentially, between 2,546,669 3/1951 Kirby surface-engagement and thrusting cycles, to define a 2,612,346 9/1952 Nelson circular bore. The apparatus disclosed comprises an 2,810,547 10/1957 Fehlmann embodied means for carrying out the novel method. 3,047,081 7/1962 Pitcher .1 175/20 X 3,163,241 12/1964 Daigle et a1 175/20 X 9 Claims, 2 Drawing Figures 62 IO sea; 54 34 We Y 11 B 111 11 1e 58 U.S. Patent Dec. 16, 1975 T E MNQS H mm mm a mt mwwzxoik QEQEQZEUZE 5 23 8 wmo on Q? METHOD OF BORING ROCK This invention pertains to apparatus for, and methods of boring rock, particularly in an axial direction, for forming tunnels, raises, and the like. as well as for long wall mining, and in particular to suchmethod and apparatus which comprises use of drill bits or cutterheads, and the like, effective for fracturing or otherwise disintegrating rock in a plane across the face thereof, and wherein the drill bit or cutterhead is rotated about an axis to cause failure, fracture, and disintegration of the rock fully across the face.

Prior art methods and apparatus of this type have comprised rotatable cutterheads carrying a plurality of perhaps fixed, but usually roller cutters in which the cutterhead is put under high thrust loading against the rock face and with the use of high torque energy the cutterhead is simultaneously rotated against the face of the rock. Such apparatus is complex, and expensive of manufacture and operation in that it is necessary to have both high thrust for engaging the rock face as well as very high torque energy, to be able to rotate the cutterhead under axial thrust loading in order to effect a full rotary boring of the rock. Clearly, it would offer an economy of structure and energy if it were possible to practice rock boring methods, and employ rock boring apparatus, which required only high thrust loading, and which could dispense with the high torque forces required in the prior art. It is an object of this invention, then to set forth a method of boring rock along an axis, comprising the steps of positioning rock cutter means in contacting engagement with a surface of rock; and applying only an axially-directed thrust force to said rock cutter means, to cause localized failure to said surface. Further it is an object of this invention to disclose an apparatus for boring rock along an axis, comprising rock cutting means, means supporting said rock cutting means; and means coupled to said supporting means for applying an only axially-directed thrusting force, which is substantially devoid of kinetic energy, to said rock cutter means; wherein said force-applying means comprises means for applying directly to said rock cutting means an incremental pressure which ranges from a minimum value of zero to a given predetermined maximum value. Further objects of this invention, as well as the novel features thereof, will become more apparent by reference to the following description taken in conjunction with the accompanying figures in which:

FIG. 1 is a diagrammatic outline of an apparatus which comprises one embodiment of the invention, the same being capable of performing the novel rock boring method; and

FIG. 2 is an isometric diagram illustrative of the rock boring pattern which proceeds from the use of the apparatus of FIG. 1 and comprehended by the practice of the novel method.

As shown in FIG. 1, the apparatus comprises a frame 12 which carries a pair of thrust cylinders 14 each of which encloses a reciprocatible piston 16. Extending piston rods 18 are threaded intermediate the length thereof to receive a translating crosshead 20. The crosshead has a pair of parallel, correspondingly threaded bores 22 formed therein threadedly to engage rods 18. Too, the crosshead comprises one, innermost end of a drill rod assembly 24, at the other end of which assembly is carried a cutter element 26. In this embodiment, as best seen in FIG. 2, the cutter element 26 is defined as a drill bit having cutters 28 in a cruciform pattern thereon. The piston rods 18, at the outermost, terminal ends thereof are rotatably supported in a frame 30. Frame 30 has journals 32 formed therein to receive rods 18, and it is centrally bored as well, at 34, to allow the drill rod assembly 24 to translate axially therethrough. The frame 30 carries a drive actuator 36 which comprises a bi-rotational motor for powering a sprocket 38 with which a drive chain (not shown) is engaged. The terminal ends of the piston rods also each carry a sprocket 38 which are in common engagement with the chain. Thus, when the drive actuator 36 is energized to rotate sprockets 38, 38, the piston rods 18 are rotated, in common, to cause the crosshead 20 to traverse axially, either to retract or advance the drill rod assembly 24.

The threaded piston rods 18 are moved outwardly (to the right, FIG. 1) under the influence of hydraulic fluid which is pressured by compressed air. Both thrust cylinders 14 are coupled by conduits 40 to a hydraulic manifold 42 which, in turn, is coupled to a cycling master or booster cylinder 44. Cylinder 44 has a piston 46 which is reciprocated by compressed air. A cycling valve 48 interposed in a compressed air feed line 50 repetitively admits compressed air into, and dumps air from, cylinder- 44 to pressure and to relieve the hydraulic fluid 52. The compressed air feed line also has a branch line 53 which, by means of an air manifold 54, supplies compressed air to the opposite or non-working sides of the pistons 16 in the thrust cylinders 14. By this arrangement, when the booster cylinder 44 depressures the hydraulic fluid, the compressed air serves as an air spring which resiliently returns the pistons 16 to their retracted positions. At the non-drilling end of the apparatus 10 is carried a thrust reaction pad 56 for emplacement against a wall of rock to react the thrust of the drill rod assembly 24.

The invention resides in the novel method of rock boring, with inventive apparatus 10, or the like, in which the cutter element 26 is first placed in engagement with a surface of the rock, then it is subjected to high thrust pressure, then withdrawn, then indexed rotationally, about the boring axis, then repositioned against the rock face, and again subjected to high thrust force. Thus, to effect indexing, an indexing motor unit 58 is carried by the crosshead 20. Unit 58 comprises a motor which drives a pinion 60 which engages a ring gear 62 carried by the drill rod assembly 24. Through the use of control means (not shown the same being within the skill of those practiced in this art) it is arranged to have the unit 58 index the drill rod assembly intermediate those times when the thrust cylinder pistons 16 are being advanced by compressed air pressured hydraulic fluid. That is, when the thrust cylinder pistons 16 are retracted, the cutter element 26 is indexed for engaging the rock in a next rotated position.

FIG. 2 depicts the cutters 28, of cutter element 26, arrayed in a crucifonn pattern in which, only by way of example, the same comprises a diameter of 5 feet (1.524 meters). Assuming a thrust force of one million, 200,000 pounds equally distributed across the cutter element 26, it is calculated that some 10,000 pounds of thrust force will obtain at each inch (2.54 centimeters) along the cutters 28. In any one of the indexed positions, the cutter element 26 will have an overall ad vance of approximately 0.033-inch (0.83 millimeter) into the rock surface.

The invention comprehends indexing the cutter ele ment 26 approximately 16 of are so that, with each indexing, the cutters 28 attack the rock face at locations intermediate those where, immediately before, cutters 28 had engaged the rock. By this means rock will be broken away, on an average, in substantially helical patterns. Also, with each indexed thrust, it is calculated that the cutters 28 will penetrate (i.e., break out rock chips with a thickness of) 0.366-inch (0.93 centimeter) approximately, assuming the aforedescribed cutter element and thrust force.

Control means proposed for the apparatus is that which, for example, will effect an indexing rate (i.e., the 16 rotational re-orientations) of 120 indexings per minute. Thus, the cutter element 26 will execute approximately five and a third full revolutions each minute, and each half second the element 26 will be executing a full thrust against the rock face.

These figures are only exemplary, of course. Penetration depth and rock-chip sizes will vary with rock face and vein hardness, will depend upon the overall thrust force applied (which may range from a half million pounds, or less, to three million pounds, or more), the configuration of cutter elements, the size of the latter (and bore diameter, therefore), etc. Obviously, with a smaller bore, and greater thrust force, or with an accelerated indexing rate, the penetration rate will be greater (rock hardness being the same). Too, in lieu of knife-edge cutters 28, the cutter element could employ other cutting means, such as carbide button bits in an optimum-patterned array (where, radially-outwardly, such button bits would be spaced apart in progressively decreasing intervals).

The control means contemplated is not disclosed; as noted, such is believed to be well within the capability of those skilled in the art. Within that frame of reference, then, it is proposed that the control means be as efficient as possible, automating indexing as immediately as possible following thrusting. In the preceeding text I explain the inventive method as comprising indexing following thrusting, and removing the rock cutter from rock engagement before indexing Obviously, the more efficient control means is that which will index during the time that the rock cutter is both withdrawing from the rock and then returning into closure therewith. Preferably, then indexing would be accomplished simultaneously with retraction and advance of the cutter elementexcepting for the very brief times, during initial retraction and final closure onto the rock face, when the cutter may be locked into rock-fracture fissures. As the apparatus 10 has no significant torque power, indexing needs to be deferred only for three finite rock engagement time spans.

The apparatus 10, and the method disclosed herein which can be practiced with the apparatus, have an uncommon efficiency as substantially all of the provisioned power and energy are used in breaking and boring rock. Too, the invention offers enhanced reliability and lower manufacturing, operating and maintenance costs particularly as rolling cutters and bearings and seals therefor are not required.

While I have described my invention in connection with a specific embodiment thereof, and particular method steps, it is to be clearly understood that this is done only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the appended claims. For instance, while the apparatus depicted herein comprises means for in- 4 dexing cutter elements about an axis, it will be apparent to those skilled in the art, taking teaching from my disclosure, that other apparatus having means for indexing cutter elements through different planes can readily be constructed. In keeping with this latter consideration, then, such apparatus would engage and thrust against the rock face along a given linear plane, be retracted, and re-engaged with the rock face in a second linear plane either parallel to our transverse to the other. Simply, my novel method teaches a high thrust bon'ng technique which can be used not only with axially rotatable cutter elements, but with other types of cutter elements and apparatus as well, to form circular, rectilinear, etc. bores as desired.

I claim: 1. A method of boring rock along an axis, comprising the steps of:

positioning rock cutter means in contacting engagement with a surface of rock; and applying only an axially-directed thrust force to said rock cutter means, to cause localized failure to said surface; wherein said positioning step comprises disposing said rock cutter means in engagement with rock in a given plane which bisects the boring axis; and further including indexing said rock cutter means, rotationally, from said given plane and re-positioning said rock cutter means in engagement with rock in another plane which bisects the boring axis; and again applying only an axially-directed thrust force to said rock cutter means. 2. A method of boring rock, according to claim 1, wherein:

said force-applying step comprises applying an incremental force. 3. A method of boring rock, according to claim 1, wherein:

said positioning step comprises engaging rock with rock cutter means having fixed rock cutter elements. 4. A method of boring rock, according to claim 1, wherein:

said indexing step comprises rotating said rock cutter means about said axis approximately 16 of arc. 5. A method of boring rock, according to claim 1, further including:

removing said rock cutter means from rock engagement prior to indexing thereof. 6. A method of boring rock, according to claim 5, wherein:

said removing, indexing, and re-positioning and force-applying steps are performed successively, said indexing step being performed prior to said repositioning and force-applying step and following said removing step; and said successive steps are performed repetitively. 7. A method of boring rock, according to claim 6, wherein:

said successive steps are performed a plurality of times each minute. 8. A method of boring rock, according to claim 6, wherein:

said successive steps are performed approximately times each minute. 9. A method of boring rock along an axis, comprising the steps of:

positioning rock cutter means in contacting engagesaid force-applying step comprises applying a force ment with a surface of rock; and taken from a range of from one-half million pounds applying only an axially-directed thrust force to said to three million pounds of thrust to said rock cutter rock cutter means, to cause localized failure to said 5 means.

surface; wherein 

1. A method of boring rock along an axis, comprising the steps of: positioning rock cutter means in contacting engagement with a surface of rock; and applying only an axially-directed thrust force to said rock cutter means, to cause localized failure to said surface; wherein said positioning step comprises disposing said rock cutter means in engagement with rock in a given plane which bisects the boring axis; and further including indexing said rock cutter means, rotationally, from said given plane and re-positioning said rock cutter means in engagement with rock in another plane which bisects the boring axis; and again applying only an axially-directed thrust force to said rock cutter means.
 2. A method of boring rock, according to claim 1, wherein: said force-applying step comprises applying an incremental force.
 3. A method of boring rock, according to claim 1, wherein: said positioning step comprises engaging rock with rock cutter means having fixed rock cutter elements.
 4. A method of boring rock, according to claim 1, wherein: said indexing step comprises rotating said rock cutter means about said axis approximately 16* of arc.
 5. A method of boring rock, according to claim 1, further including: removing said rock cutter means from rock engagement prior to indexing thereof.
 6. A method of boring rock, according to claim 5, wherein: said removing, indexing, and re-positioning and force-applying steps are performed successively, said indexing step being performed prior to said re-positioning and force-applying step and following said removing step; and said successive steps are performed repetitively.
 7. A method of boring rock, according to claim 6, wherein: said successive steps are performed a plurality of times each minute.
 8. A method of boring rock, according to claim 6, wherein: said successive steps are performed approximately 120 times each minute.
 9. A method of boring rock along an axis, comprising the steps of: positioning rock cutter means in contacting engagement with a surface of rock; and applying only an axially-directed thrust force to said rock cutter means, to cause localized failure to said surface; wherein said force-applying step comprises applying a force taken from a range of from one-half million pounds to three million pounds of thrust to said rock cutter means. 